A man complains of short-term pain attacks caused by cold stimuli in the tooth on his upper left jaw, which have been observed for the last 3 weeks. Objective examination of the 25 revealed a Black’s I class carious cavity located within mantle dentin. The cavity has narrowopening, its walls and floor are covered with softened dentin. Probing is painful along the dentin-enamel border, percussion is painless, thermometry is painful, the pain quickly abates after removal of a stimulus. Electric pulp test is 6 microamperes. Make the diagnosis: